Hi, I'm wondering if anyone can help with my gardenias. They have what looks
like a black mould or soot all over the leaves. Am I correct in assuming it
is scale or is it a fungus. We have had very hot summers and the plants
probably haven't had enough water and fertilisation. I have recently learnt
that they do need a bit of feeding.
Thanks

Jenny & Mark Brodie wrote:

Hi, I'm wondering if anyone can help with my gardenias. They have what looks
like a black mould or soot all over the leaves. Am I correct in assuming it
is scale or is it a fungus. We have had very hot summers and the plants
probably haven't had enough water and fertilisation. I have recently learnt
that they do need a bit of feeding.
Thanks

Gardenias require acidic, fast-draining soil that is always moist
but never really wet. When I planted my gardenia, I mixed a
generous amount of peat moss into the soil. Once a year, I
sprinkle some soil sulfur around it. About twice a year, I add
enough gypsum to hide the soil, which is heavy adobe clay. The
gypsum keeps the clay porous and improves drainage.

They are heavy feeders. I feed my gardenia whenever I feed my
dwarf citrus, lightly twice a month from early April through mid
October. I alternate, using citrus food (yes on the gardenia) and
ammonium sulfate. Each time I feed, I also add a large pinch of
zinc sulfate.

--

David E. Ross
URL:http://www.rossde.com/

I use Mozilla as my Web browser because I want a browser that
complies with Web standards. See URL:http://www.mozilla.org/.

Jenny & Mark Brodie wrote:
Hi, I'm wondering if anyone can help with my gardenias. They
have
what looks like a black mould or soot all over the leaves. Am I
correct in assuming it is scale or is it a fungus. We have had
very hot summers and the plants probably haven't had enough
water
and fertilisation. I have recently learnt that they do need a
bit
of feeding.
Thanks

The black stuff is most probably sooty mold is growing on the
excrement of aphids.

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Travis in Shoreline (just North of Seattle) Washington
USDA Zone 8
Sunset Zone 5